Maybe a Step 'Backwards', But Handy?

Spiffy · Jun 6, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Since the rod side displaces less fluid, I think you'd need an expandable bladder, but then it would have some spring back effect as a bonus!

Sounds like a neat idea, even if that means I'll have one less good reason too talk you green guys into manual valves. /forums/images/graemlins/frown.gif /forums/images/graemlins/grin.gif

Spiffy · Jun 6, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Since the rod side displaces less fluid, I think you'd need an expandable bladder, but then it would have some spring back effect as a bonus!

Sounds like a neat idea, even if that means I'll have one less good reason too talk you green guys into manual valves. /forums/images/graemlins/frown.gif /forums/images/graemlins/grin.gif

BobRip · Jun 6, 2006

Re: Maybe a Step \'Backwards\', But Handy?

This is getting complicated. I will try to think of another way.

If I use a bladder I would have to valve it out for normal operation. This would take an additional valve. Is a bladder a commercial device?

Has anyone got some suggestions?

Bob Rip

BobRip · Jun 6, 2006

Re: Maybe a Step \'Backwards\', But Handy?

This is getting complicated. I will try to think of another way.

If I use a bladder I would have to valve it out for normal operation. This would take an additional valve. Is a bladder a commercial device?

Has anyone got some suggestions?

Bob Rip

Spiffy · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

 Has anyone got some suggestions?


Doubt any are too much simpler, but you did ask for suggestions not "good suggestions"... /forums/images/graemlins/grin.gif

How about a double rod cylinder? Displacements would be equal.

Bladders are made for Ag and off-road equipment, but I have no idea of pricing. The diaphram type here is probably even more appropriate than the bladder type here; but either is available in around a quart which should be fine.

Replace the cylinder with a heavy spring.

Mount a portable air tank on the lift arms; I wouldn't be surprised if 200 psi would be enough to actuate it. You could even still run the cylinder on oil/ and or charge it with oil, but in the latter case would need to pay close attention to the pressure when you recharge it.

Did I mention adding a valve bank? /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Spiffy · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

 Has anyone got some suggestions?


Doubt any are too much simpler, but you did ask for suggestions not "good suggestions"... /forums/images/graemlins/grin.gif

How about a double rod cylinder? Displacements would be equal.

Bladders are made for Ag and off-road equipment, but I have no idea of pricing. The diaphram type here is probably even more appropriate than the bladder type here; but either is available in around a quart which should be fine.

Replace the cylinder with a heavy spring.

Mount a portable air tank on the lift arms; I wouldn't be surprised if 200 psi would be enough to actuate it. You could even still run the cylinder on oil/ and or charge it with oil, but in the latter case would need to pay close attention to the pressure when you recharge it.

Did I mention adding a valve bank? /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

J_J · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

A motor spool valve is designed to allow a motor to coast to a stop when the valve is in neutral, therefore the pressure would bleed off to the tank. You never want to stop a running motor by using a closed center valve. The dynamic forces on that motor might build up enough pressure to blow the lines, fittings or whatever. If that spool valve is used on a cylinder, the cylinder will bleed down and loose all pressure, maybe causing a bucket or arm to drop.

What kind of hydraulic circuit are you using the spool valve?

J_J · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

A motor spool valve is designed to allow a motor to coast to a stop when the valve is in neutral, therefore the pressure would bleed off to the tank. You never want to stop a running motor by using a closed center valve. The dynamic forces on that motor might build up enough pressure to blow the lines, fittings or whatever. If that spool valve is used on a cylinder, the cylinder will bleed down and loose all pressure, maybe causing a bucket or arm to drop.

What kind of hydraulic circuit are you using the spool valve?

J_J · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

An accumulator is designed to hold pressure and absorb some of the shock effects of hydraulic circuits. You want to be careful when using these in a circuit. Even with the engine and pump off, and you activate one of the valves, you will have full pressure until the accumulator is empty.

J_J · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

An accumulator is designed to hold pressure and absorb some of the shock effects of hydraulic circuits. You want to be careful when using these in a circuit. Even with the engine and pump off, and you activate one of the valves, you will have full pressure until the accumulator is empty.

Spiffy · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Excellant description of the two types JJ! As you noted the true reason for the open "neutral" postion is coasting to a stop; but a real bonus for the PT is how it makes connections so much easier - without even turning off the engine.

I'm using a motor spool to the PTO, and a cylinder spool to the BH (since it already has open center no risk of dynamic pressure forces). My valve has another cylinder spool I'm not currently using, but that's only because the 3 spool happend to be a good buy at the time (it'd be way too big on a 425 though).

Anyway, at the risk of my verbosity causing more confusion, the 425 configuration in question would be identical (motor spool to PTO), except the cylinder spool would go to auxillary hydraulics like grapples etc.

Does that make more or less sense? /forums/images/graemlins/crazy.gif

Spiffy · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Excellant description of the two types JJ! As you noted the true reason for the open "neutral" postion is coasting to a stop; but a real bonus for the PT is how it makes connections so much easier - without even turning off the engine.

I'm using a motor spool to the PTO, and a cylinder spool to the BH (since it already has open center no risk of dynamic pressure forces). My valve has another cylinder spool I'm not currently using, but that's only because the 3 spool happend to be a good buy at the time (it'd be way too big on a 425 though).

Anyway, at the risk of my verbosity causing more confusion, the 425 configuration in question would be identical (motor spool to PTO), except the cylinder spool would go to auxillary hydraulics like grapples etc.

Does that make more or less sense? /forums/images/graemlins/crazy.gif

Spiffy · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Even with the engine and pump off, and you activate one of the valves, you will have full pressure until the accumulator is empty. 

Good point; it would always be under whatever pressure you charge it too (3ksi, if allowed to fully charge - though that'd be 60% capacity on a 5ksi accumulator).

Of course, for the expense, time, and effort there; not to mention having stored energy on the system even if turned off; I do like valving options much better.

Spiffy · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Even with the engine and pump off, and you activate one of the valves, you will have full pressure until the accumulator is empty. 

Good point; it would always be under whatever pressure you charge it too (3ksi, if allowed to fully charge - though that'd be 60% capacity on a 5ksi accumulator).

Of course, for the expense, time, and effort there; not to mention having stored energy on the system even if turned off; I do like valving options much better.

J_J · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

I agree, that makes perfectly good sense.

J_J · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

I agree, that makes perfectly good sense.

catsco · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Thanks all for the discussion and suggestions.

I think I'll try to fabricate a "T" with a diverter valve or two valves on it to connect to the tractor.

Then, flip the valve (or close one and open the other) on each side, disconnect hoses, then swap attachments, reconnect attachment hoses, then flip the valve (or close one and open the other).

This shortens the procedure. Obviously, the attachment hoses still much be detached and attached.

Seems like the lowest cost solution, and avoids the extra two hose swaps to power the release mechanism.

Mark H.

catsco · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Thanks all for the discussion and suggestions.

I think I'll try to fabricate a "T" with a diverter valve or two valves on it to connect to the tractor.

Then, flip the valve (or close one and open the other) on each side, disconnect hoses, then swap attachments, reconnect attachment hoses, then flip the valve (or close one and open the other).

This shortens the procedure. Obviously, the attachment hoses still much be detached and attached.

Seems like the lowest cost solution, and avoids the extra two hose swaps to power the release mechanism.

Mark H.

Barryh · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Man you are good. Spiffy too. I know my machine has hydraulics, but it pretty much ends there. /forums/images/graemlins/confused.gif

Barryh · Jun 7, 2006

Re: Maybe a Step \'Backwards\', But Handy?

Man you are good. Spiffy too. I know my machine has hydraulics, but it pretty much ends there. /forums/images/graemlins/confused.gif